Some industrial, scientific, medical, and commercial activities involve workers performing tasks at work tables which result in the production of any of a number of noxious or unpleasant substances to which those workers might be exposed as they carry out their activities. Some examples of such activities include the performance of autopsies, dissections, and embalming procedures, the fabrication of electronic circuitry, the manipulation of toxic substances such as hazardous chemicals or biological material, or any activity which might produce airborne contamination.
In the past, efforts have been made to ventilate the work areas where these kinds of activities are carried out. In some instances, specially designed ventilation systems have been constructed for the room where the activity of concern is being carried out. In other instances, individual work tables or work stations in the room have been ventilated in some manner in an attempt to further protect workers from being exposed to undesirable contamination. In none of these cases has a system been devised which permits a sufficiently versatile, efficient, or controllable ventilation system for a work area. In addition, many of such ventilation systems have been cumbersome in that they are constructed so that they take up too much space and restrict a worker's activities, for example, as in laboratory fume hoods which allow access only from the front. In some cases, those fume hoods further restrict access in the front by the use of windows or sashes.
For example, U.S. Pat. No. 3,701,514 refers to a table used in cutting steel plate. The table has a series of channels extending under a grating which supports a metal workpiece undergoing a cutting operation. There is a hinged cover for each of the channels which opens when a plasma cutting torch is situated over its respective channel or over a channel adjacent to its respective channel. When a hinged cover opens, its channel is connected to an exhaust manifold so that the channel is exhausted of the fumes and smoke produced by the cutting operation. At other times, each of the hinged covers seals its respective channel from the manifold and the channel is not exhausted. Plainly, this type of an arrangement permits the ventilation of only a small part of the work surface at any one time. Moreover, it does not permit the ventilation to be controlled in any meaningful manner, either over a small area encompassed by a single channel or over a larger area encompassed more than one channel.
U.S. Pat. No. 3,715,972 deals with a laminar flow clean work station composed of interchangeable work modules containing items such as sinks, hot plates and the like, each of which is connected to a common exhaust plenum. Each of the modules has a separate exhaust damper suitable for the particular exhaust requirement of each module. There is no suggestion about how to provide proper and controllable ventilation of a large area work surface.
U.S. Pat. No. 3,894,480 refers to a laboratory bench having an exhaust plenum with an inlet vent above a table top. The exhaust plenum is divided into a number of exhaust chambers, each containing an intake mouth of an exhaust conduit. Dampeners in a chimney connected to the exhaust conduits control the intake flow from the chambers of the exhaust plenum. This arrangement does not provide sufficient or controllable ventilation over the entire surface of a work table.
U.S. Pat. No. 4,100,847 deals with a laminar airflow cabinet having an adjustable damper for changing the airflow pattern in the cabinet to supposedly meet specialized ventilation requirements when working with potentially hazardous biological substances. A knee well is provided in the front of the cabinet. U.S. Pat. Nos. 3,926,597 and 4,098,174 also refer to knee spaces in laminar flow cabinets.
None of the patents described above deal with a device which is able to effectively and controllably ventilate the entire surface of a work table. None of them show an apparatus which provides adequate ventilation while at the same time providing convenient and comfortable operator access to three or four sides of a work table. They are indicative of a long felt and unfulfilled need for such a device and of many attempts to satisfy that need without success.
The invention of this application addresses this need for a superior ventilated work table not provided by the prior efforts of others.
Accordingly, it is an object of the invention to provide a work table which is adequately ventilated to prevent workers from being exposed to noxious and harmful substances when working at the table.
It is an additional object of the invention to provide a work table in which the adequate ventilation is provided over the entire work surface of the table.
It is another object of the invention to provide a work table in which the amount of ventilation is controllable over the entire surface of the table.
It is also an object to provide a ventilated work table which does not interfere with the activities of workers using the work table.
It is also an object of the invention to provide a ventilated work table which is capable of effectively and controllably evacuating both wet and dry substances, including gases containing liquid droplets and solid particulate matter, from the surface of the work table.
Other objects and advantages are either specifically described elsewhere in this application or are apparent from that description.